1. Field of the Invention
The present invention relates to a display device and a method of manufacturing a display device.
2. Description of the Related Art
In recent years, a thin display device such as an organic EL display device or a liquid crystal display device has remarkably developed, because of its features such as thinness, light weight, and low power consumption, as a possible substitute for a CRT, which had conventionally been in the mainstream of display devices. Especially a high resolution of a display image has developed, which requires the technique for manufacturing a color filter suitable for a display device having a high resolution.
The size of one pixel is reduced as the resolution of the display device becomes higher, so that it is necessary to form a light-shielding film having a small interval between patterns. However, forming the light-shielding film using photolithography causes a problem in that the light-shielding film having a shape as designed cannot be obtained as the interval between the patterns becomes smaller. This problem will be described with reference to FIGS. 10A to 10C.
FIG. 10A represents a photomask 1000 used for forming a light-shielding film. Here, when, for example, photolithography is performed using a positive photoresist whose solubility in a developer increases upon exposure, a light-shielding film having a shape shown in FIG. 10B is obtained due to light diffraction, scattering, or the like occurring at portions where an interval between patterns 1002 formed in the photomask 1000 is small. Moreover, when, for example, photolithography is performed using a negative photoresist whose solubility in a developer decreases upon exposure, a light-shielding film having a shape shown in FIG. 10C is obtained for a similar reason.
Therefore, for example, JP 2014-228723 A describes that portions of different amounts of exposure are provided in a picture-frame portion of a black matrix to form concave and convex patterns. In addition, JP 2014-228723 A discloses that, by reducing the activity of a developer in the vicinity of the picture-frame portion, the occurrence of narrowing or constriction of the line width of the black matrix located in the vicinity of the picture-frame portion is prevented in a color filter having a small interval between patterns.
Moreover, for example, JP 2014-145924 A discloses a method of manufacturing a light-shielding film substrate, in which a light-shielding film is formed in multiple separate steps and an interval of the light-shielding film formed in one step is widened to thereby narrow the line width of the light-shielding film.